Adding a 3 band EQ to a Muff?

[south_saturn]

I've had a little idea which involves adding a 3-band EQ to a Big Muff circuit. The plan is to make it switchable between the EQ and the original tone stack. The thing is I am fairly new to the DIY thing having only built 6 pedals so far and I'm not 100% on how to implement this. What I would like to do with this project is create my own PCB layout which will be a first for me. I have quite a bit of reading to do I know but I would like to ask for a little help in choosing an EQ circuit to use in this project.

So basically, in leyman's terms I am looking at:

Input -> Muff (Q1, 2 and 3) -> big muff tone stack -> Q4/output pot -> output
                                        -> 3 band eq

I don't know if this is practicably possible or will be all that effective but I would like some comments/suggestions if you have the time.

Roy

P.S. would it be possible to adapt something like the Dr. Boogey EQ section for use in this circuit?

[petemoore]

Input -> Muff (Q1, 2 and 3) -> big muff tone stack -> Q4/output pot -> output
                                        -> 3 band eq
  It might be just the thing. However you'll be having two tonestacks 'almost in a row [as I imagine Q4 as a recovery gain stage.
  And Q4 would also be a drive stage for the 3 band Eq, whether there's enough oomph after 2 passive loss circuits [tone controls] with 1 x Q4 to have enough output is another question.
  What does 'output' refer to ?
  Assuming output pot = volume control, it could be placed at the end.
  I suggest ditch the BM tonestack, put the volume control at the end:
  Muff>3band EQ>Q4>Volume>
  I'm not sure what the output of the muff is and how well it'd drive a tonestack either.
 

[south_saturn]

Sorry I guess I should have clarified it somewhat, I am just getting my head around what each part of the circuit actually does 

Output refers to the output jack i guess. With regards to the two tone stacks; I would like to make them switchable as using a parametric EQ in place of the BMP stack changes the muff character and I would like the original tone stack to be an option at any given time.

[petemoore]

-> Muff (Q1, 2 and 3)
  It is three gain stages, pre-filtering of some sort [is different than post filtering] smaller staging caps could do this.
-> big muff tone stack
  Passive components which load the signal path, raises impedance and lowers output.
   -> Q4
  'Recovery stage', a gain stage which boosts what is left of the signal after the passive TC uses some of what the Muff delivers.
  /output pot
  Also loads signal to some degree.
    -> 3 band eq Passive components again attenuate signal, in a frequency specific fashion.
  "Recovery stage I believe is 'like english' in that a gain stage is called this when following a TC, or is otherwise boosting a weak signal.
  It seems from my exp. that the more 'stuff' I run the signal through, the less 'there' it tends to sound...which isn't even true, because filtering 'along the way' seems necessary, often times I'll simple choose values for fixed positions depending on what I want, and add a position [such as a simple treble control, or fixed LP filter] as necessary.

[Gila_Crisis]

check this:
http://www.muzique.com/lab/atone.htm

http://www.muzique.com/lab/tone3.htm

[ubersam]

Think about how you would wire a bypass switch. It would be the same but instead of a piece of wire (as it would have been for a bypass switch), you'll have the 3 band EQ circuit instead. I can draw up a quick schematic if my description is unclear. I imagine that would cause some pops so you might want to consider JFET switching instead of mechanical.

[south_saturn]

check this:
http://www.muzique.com/lab/atone.htm

http://www.muzique.com/lab/tone3.htm

Excellent info from Jack there. I guess I didn't look very hard  Is the AMZ ebook worth buying do you think?

As for wiring I was hoping to be able to integrate the eq into the circuit as opposed to having a seperate board and running it Muff -> EQ if possible. I'll have a good read through Jack's articles today and if I have any more questions I'll be sure to ask. Thanks guys!

[Mark Hammer]

It's just my view, but I think once you understand the BMP tone circuit a bit better, you may find that simply inserting a couple of options to the basic BMP circuit will give you all the tonal flexibility you seek.  I'm certainly not dissing your choice to have the either/or option.  However, that's a heap more parts, 3 knobs, 3 pots, and more wiring....lots more wiring.  There may well be a lot more, though, in the simple addition of two toggle switches and a few component changes to the BMP than first seems apparent to the naked eye.

[south_saturn]

Thanks Mark this definitely gives me something to think about.

I have been reading a little today about the circuit and I think I understand it a little better, especially the tone stack/filters thanks to the AMZ articles. I would still like to have a bit of a tinker with the circuit to try and get a bit more out of it.

more reading...

[DiamondDog]

check this:
http://www.muzique.com/lab/atone.htm

http://www.muzique.com/lab/tone3.htm

Excellent info from Jack there. I guess I didn't look very hard  Is the AMZ ebook worth buying do you think? . Thanks guys!

I have it; I got it for the Rat part of the set (and what a good move that was... It gave me ideas to move even further and ended up with a pedal I love. )

If you want to get all the nitty gritty on the circuit, yes. Get it. I am sure Jack won't mind me saying that there's nothing in it that you can't find elsewhere. But you have to find it elsewhere first!

Also get all of Jack's papers on the BMP tone stack, including presence controls etc. for a full understanding of not only what it is, but some of the directions you can go with it. Then break out the breadboard and experiment away!

And get the AMZ CD while you're at it!

(I'm not affiliated with Jack in any way- He is one of several people who, when they speak, I listen...

Speaking of which- RG- why is there no "Technlogy of the Big Muff" on geofex.com